package com.mzj.saas.commons;

import org.apache.commons.codec.binary.Base64;
import org.springframework.util.StringUtils;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.math.BigInteger;


public class AESUtil {


    //密钥 (需要前端和后端保持一致)
    private static String KEY;

    private static AESUtil instance;

    public static AESUtil getInstance(String secretKey) {
        KEY = secretKey;
        if (instance == null) {
            instance = new AESUtil();
        }
        return instance;
    }

    //算法
    private static final String ALGORITHMSTR = "AES/CBC/PKCS5Padding";

    /**
     * aes解密
     * @param encrypt   内容
     * @return
     * @throws Exception
     */
    public static String aesDecrypt(String encrypt, String ivParameter) {
        try {
            return aesDecrypt(encrypt,ivParameter, KEY);
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    /**
     * aes加密
     * @param content
     * @return
     * @throws Exception
     */
    public static String aesEncrypt(String content, String ivParameter) {
        try {
            return aesEncrypt(content,ivParameter,KEY);
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    /**
     * 将byte[]转为各种进制的字符串
     * @param bytes byte[]
     * @param radix 可以转换进制的范围，从Character.MIN_RADIX到Character.MAX_RADIX，超出范围后变为10进制
     * @return 转换后的字符串
     */
    public static String binary(byte[] bytes, int radix){
        return new BigInteger(1, bytes).toString(radix);// 这里的1代表正数
    }

    /**
     * base 64 encode
     * @param bytes 待编码的byte[]
     * @return 编码后的base 64 code
     */
    public static String base64Encode(byte[] bytes){
        return Base64.encodeBase64String(bytes);
    }

    /**
     * base 64 decode
     * @param base64Code 待解码的base 64 code
     * @return 解码后的byte[]
     * @throws Exception
     */
    public static byte[] base64Decode(String base64Code) throws Exception {
        return StringUtils.isEmpty(base64Code) ? null : Base64.decodeBase64(base64Code);
    }

    /**
     * AES加密
     * @param content 待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的byte[]
     * @throws Exception
     */
    public static byte[] aesEncryptToBytes(String content, String ivParameter, String encryptKey) throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        keyGenerator.init(128);
        Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
        IvParameterSpec iv = new IvParameterSpec(ivParameter.getBytes());//使用CBC模式，需要一个向量iv，可增加加密算法的强度
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(encryptKey.getBytes(), "AES"),iv);

        return cipher.doFinal(content.getBytes("utf-8"));
    }


    /**
     * AES加密为base 64 code
     * @param content 待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的base 64 code
     * @throws Exception
     */
    public static String aesEncrypt(String content, String ivParameter, String encryptKey) throws Exception {
        return base64Encode(aesEncryptToBytes(content, ivParameter,encryptKey));
    }

    /**
     * AES解密
     * @param encryptBytes 待解密的byte[]
     * @param decryptKey 解密密钥
     * @return 解密后的String
     * @throws Exception
     */
    public static String aesDecryptByBytes(byte[] encryptBytes, String ivParameter, String decryptKey) throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        keyGenerator.init(128);

        Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
        IvParameterSpec iv = new IvParameterSpec(ivParameter.getBytes());//使用CBC模式，需要一个向量iv，可增加加密算法的强度
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(decryptKey.getBytes(), "AES"),iv);
        byte[] decryptBytes = cipher.doFinal(encryptBytes);
        return new String(decryptBytes);
    }


    /**
     * 将base 64 code AES解密
     * @param encryptStr 待解密的base 64 code
     * @param decryptKey 解密密钥
     * @return 解密后的string
     * @throws Exception
     */
    public static String aesDecrypt(String encryptStr, String ivParameter, String decryptKey) throws Exception {
        return StringUtils.isEmpty(encryptStr) ? null : aesDecryptByBytes(base64Decode(encryptStr),ivParameter, decryptKey);
    }


    /**
     * 测试
     */
    public static void main(String[] args) throws Exception {
        AESUtil aesUtil = AESUtil.getInstance("E847BB99CC1B7EB2C3059A74C3F386F4");
        /*String openId = "oQGo46FGTMZI2oq85u2GL6Vx4r6M";
        String UnionId = "oYPNW6MujvmzlALqINWdzStJz8sI";
        String AppId = "wx4384ceefb948380a";
        System.out.println("加密前：" + UnionId+AppId+openId);
        System.out.println("密钥：" + KEY);
        String encrypt = aesUtil.aesEncrypt(UnionId+AppId+openId, "1234567890000000");
        System.out.println("加密后：" + encrypt);
        String decrypt = aesUtil.aesDecrypt(encrypt, "1234567890000000");
        System.out.println("解密后：" + decrypt);
        */
        
        String vString = "PGF+q6QemhDFMR5o+XrGYg==";
        System.out.println(String.valueOf(aesUtil.base64Decode(vString)));
        String decrypt2 = aesUtil.aesDecrypt(vString, "0102030405060708");
        System.out.println("解密后：" + decrypt2);
    }
}
